New Method to Assess Sagittal Jaw Position: TWM and TWG Angles: A Cephalometric Study

Abstract

The aim of the study was to develop new cephalometric angles TWM (T-Tuberculum sella, W-wing point, M-maxillary point) and TWG (T-Tuberculum sella, W-wing point, G point-center of mandibular symphysis) and to assess and evaluate the newly developed angles in determining the maxillary and mandibular sagittal position, respectively. Ninety pretreatment lateral cephalograms from the records of Department of Orthodontics and Dentofacial Orthopaedics were traced and divided equally into three groups as class I, class II, and class III based on cephalometric values of ANB angle and WITS appraisal. Further for each radiograph, angles such as SNA, TWM, SNB, and TWG were measured and recorded. The TWM angle (Maxilla) was formed using the points T-Tuberculum sella, W-wing point, M-maxillary point, and the TWG angle (mandible) was formed using the points T-Tuberculum sella, W-wing point, G point-center of mandibular symphysis. The mean values of TWM and TWG angles for the class I group were 120.1°± 3.6° and 101.4 ± 3.7°, respectively. The one-way analysis of variance (ANOVA) was used followed by Tukey post hoc testing to determine whether there was a statistically significant difference between the mean values of the three groups. A p value ≤ .05 was considered to be statistically significant. Pearson correlation test revealed a strong correlation between SNA and TWM angles and similarly between SNB and TWG angles. The two new angles, TWM for maxilla and TWG for mandible established, can be used as an alternative for assessing the sagittal position of the jaw bases and will give a clearer picture, as stable and reproducible landmarks are used.